OBJECTIVE To determine whether female marmosets undergo a reduction in bone mineral density following ovariectomy or socially induced hypoestrogenic anovulation. RESULTS Chronic reduction in estrogen causes a reduction in bone mineral density (BMD) and an increase in osteoporosis in most species in which it has been studied. In marmosets, socially subordinate females regularly become anovulatory and may remain hypoestrogenemic for extended periods of time. To determine whether marmosets might possess a mechanism to protect them from the deleterious skeletal consequences of hypoestrogenism, we examined the effect of ovariectomy-induced or socially induced hypoestrogenism on BMD. No differences in BMD were found between ovary-intact and ovariectomized females, or between dominant and subordinate females. A longitudinal study also failed to reveal any effects of ovariectomy on BMD. Thus, marmosets may possess a unique adaptation protecting them from hypoestrogenism-induced bone loss, and might provide a novel model for the investigation and treatment of osteoporosis. FUTURE DIRECTIONS We plan to confirm and extend our preliminary findings and to begin to investigate the possible biochemical and cellular mechanisms by which estrogen depletion is decoupled from bone loss in female marmosets. KEY WORDS dual-energy X-ray absorptiometry, skeletal system, osteoporosis FUNDING Saltzman, W., C, FED, AG15621, $62,000, NIH. PUBLICATIONS Colman, R.J., W. Saltzman, D.H. Abbott, J.W. Kemnitz, and N. Binkley. 1998. Lack of estrogen depletion bone loss in common marmosets. International Symposium on Biology of Menopause, Newport Beach, CA. [A]